mmc: sdhci-of-dwcmshc: Update DLL and pre-change delay for rockchip platform

For Rockchip platform, DLL bypass bit and start bit need to be set if
DLL is not locked. And adjust pre-change delay to 0x3 for better signal
test result.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Link: https://lore.kernel.org/r/1675298118-64243-2-git-send-email-shawn.lin@rock-chips.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Author: shawn1221

drivers/mmc/host/sdhci-of-dwcmshc.c

@@ -48,6 +48,7 @@
 #define DWCMSHC_EMMC_DLL_RXCLK_SRCSEL	29
 #define DWCMSHC_EMMC_DLL_START_POINT	16
 #define DWCMSHC_EMMC_DLL_INC		8
+#define DWCMSHC_EMMC_DLL_BYPASS		BIT(24)
 #define DWCMSHC_EMMC_DLL_DLYENA		BIT(27)
 #define DLL_TXCLK_TAPNUM_DEFAULT	0x10
 #define DLL_TXCLK_TAPNUM_90_DEGREES	0xA
@@ -60,6 +61,7 @@
 #define DLL_RXCLK_NO_INVERTER		1
 #define DLL_RXCLK_INVERTER		0
 #define DLL_CMDOUT_TAPNUM_90_DEGREES	0x8
+#define DLL_RXCLK_ORI_GATE		BIT(31)
 #define DLL_CMDOUT_TAPNUM_FROM_SW	BIT(24)
 #define DLL_CMDOUT_SRC_CLK_NEG		BIT(28)
 #define DLL_CMDOUT_EN_SRC_CLK_NEG	BIT(29)
@@ -234,9 +236,12 @@ static void dwcmshc_rk3568_set_clock(struct sdhci_host *host, unsigned int clock
 	sdhci_writel(host, extra, reg);
 
 	if (clock <= 52000000) {
-		/* Disable DLL and reset both of sample and drive clock */
-		sdhci_writel(host, 0, DWCMSHC_EMMC_DLL_CTRL);
-		sdhci_writel(host, 0, DWCMSHC_EMMC_DLL_RXCLK);
+		/*
+		 * Disable DLL and reset both of sample and drive clock.
+		 * The bypass bit and start bit need to be set if DLL is not locked.
+		 */
+		sdhci_writel(host, DWCMSHC_EMMC_DLL_BYPASS | DWCMSHC_EMMC_DLL_START, DWCMSHC_EMMC_DLL_CTRL);
+		sdhci_writel(host, DLL_RXCLK_ORI_GATE, DWCMSHC_EMMC_DLL_RXCLK);
 		sdhci_writel(host, 0, DWCMSHC_EMMC_DLL_TXCLK);
 		sdhci_writel(host, 0, DECMSHC_EMMC_DLL_CMDOUT);
 		/*
@@ -279,7 +284,7 @@ static void dwcmshc_rk3568_set_clock(struct sdhci_host *host, unsigned int clock
 	}
 
 	extra = 0x1 << 16 | /* tune clock stop en */
-		0x2 << 17 | /* pre-change delay */
+		0x3 << 17 | /* pre-change delay */
 		0x3 << 19;  /* post-change delay */
 	sdhci_writel(host, extra, dwc_priv->vendor_specific_area1 + DWCMSHC_EMMC_ATCTRL);